Contact investigation is a widely advocated strategy for extending tuberculosis (TB) case detection from clinics to communities through screening of household contacts of new TB patients and referral of at-risk patients for clinic-based confirmatory testing and treatment. Unfortunately, low rates of clinic follow-up among at-risk individuals represent a major barrier to implementing contact investigation in high-burden countries. In a formative evaluation based on a WHO-endorsed conceptual model of barriers to accessing TB evaluation services, we have identified a lack of patient knowledge about TB and TB evaluation, and economic and geographic barriers as the major determinants of this quality gap. The objective of this proposal is to determine if home sputum collection, supported by targeted, mobile-phone health (mHealth) messages and incentives, is an effective and scalable solution for overcoming these barriers to implementing contact investigation. The scientific approach will be to carry-out a household-randomized, controlled trial in five rural Ugandan communities comparing two approaches to evaluation of at-risk contacts: referral to clinics for TB testing (standard approach) vs. home sputum collection supported by mHealth interventions. We will use the RE-AIM framework for intervention evaluation to assess the patient and public-health impact of these interventions, using pre-specified measures of their reach, effectiveness, adoption, implementation, and maintenance. Specifically, we will first determine if mHealth-facilitated home sputum collection increases rates of TB and HIV diagnosis and clinic follow-up (reach), TB treatment initiation (effectiveness), and completion (maintenance), as compared to standard contact investigation. Second, we will use quantitative and qualitative methods to evaluate the internal effectiveness and fidelity of the component interventions across different sites (adoption). Third, we will employ economic and epidemic modeling to estimate the costs and epidemiological impact of this intervention (implementation). The proposed research will make a significant contribution to patient care and health policy by providing comprehensive, practice-based evidence on contact investigation in a low- income country, including whether it can be implemented more widely and efficiently by decreasing unnecessary clinic referrals and increasing early identification and treatment of infectious TB patients. We have assembled a well-established team of investigators, who will take advantage of the outstanding environment for health services research with the Uganda TB Surveillance Project. Together, they will combine their expertise in innovative, multi-disciplinary methods from clinical research, behavioral science, and applied mathematics with their extensive experience in core content areas, including TB diagnosis and contact investigation; mHealth; theories of behavior change and implementation frameworks; biostatistics; and health economics to evaluate a cutting-edge, patient-centered technological intervention.